Thermal sums

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Thermal sums refer to growing-degree days above/below a temperature threshold.

 

Indicator

Metric

Accumulated Frost

sum of degree days where Tmin < 0.0 oC [Barnett et al., 2006]

Heating Degree Days

∑(Tt - Tavg) where Tavg < Tt [Barnett et al., 2006]

Accumulated Degree Days

∑Tavg> Tc for a certain period of time* [Barnett et al., 2006]

*year, coldest month, winter trimester (December-February in the northern hemisphere; June-August in the southern hemisphere), and first semester of the year (January-June in the northern hemisphere; July-December in the southern hemisphere).

Tmin (oC): minimum air temperature

Tc (oC): critical air temperature (in general, 0 oC; base temperature for growth, e.g. 5.6 oC)

Tt (oC): threshold air temperature (e.g. 15.5 oC)

Tavg (oC): average air temperature

∑Tavg (oC-days): sum of Tavg



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